Coated abrasive article and method of manufacturing the same



Nov. 18, 194,7. H. P. KIRCHNERJ COATED ABRASIVE ARTICLE AND METHOD OFMANUFACTURING THE SAME Filed Feb. 5, 194@ Env/enfer Henry Kirchner fiforgy Patented Nov.v 18, 19.47

COATED ABRASIVE ARTICLE AND METHOD MANUFACTURING THE SAME Henry P.Kirchner, Niagara Falls, N. Y., assignor to The Carborundum Company,NiagaraFalls, N. Y., a corporation of Delaware Application February 5,1946, Serial No. 645,635

This invention relates to improved abrasive articles and to a method ofmanufacturing the samef It is particularly concerned with coatedabrasive articles in which the backing comprises discs are very likely tcrack when they are pulled up against the supporting pad by the nut I4.Likewise,if the disc has a curvature such that the abrasive side isconcave, it will not lie snugly vulcanized ber, and especially withdiscs made against the supporting pad and is very likely to from sucharticles. catch against the work and tear. f

Abrasive discs of the kind with which this in- It has been found byexperience that a desirvention is particularly concerned have beendeable curvature for the disc is such that the height scribed andclaimed in a patent to Richard P. of the cord of a disc 9% inches indiameter, which Carlton Re. 20,946. They are made by coating l0 is asize which is very commonly used, shall lie either vulcanized fiberalone or the cloth side of within the range of about 1,4, inch toabout-1 inch, a combination of cloth and vulcanized ber and andpreferably shall be about to 5A; inch. l Very large numbers of sucharticles have been, e In order to obtainl this desired degree ofcurvaand are being, made. They are used for a great ture it is commonpractice in the abrasive lndusvariety of purposes, such as the removalof excess l5 try to cure the adhesive which is used for attachmaterialfrom the welds on automobile bodies and ing the abrasive grains to websof the backing for smoothing sheet material such as automobile materialwith the webs wound into rollsY of such fenders and refrigerator boxes.diameter that the curvature of the completed ar- The method bywhichthese discs are commonly ticle falls within the desired range. l Afterthe used is described and claimed in anumberof patmaterial has been thustreated t0 Set the adents. including a, patent to Herbert R. Stratfordhesive the discs are stamped from the web ma- No. 1,686,938. Theirconstruction and method of terial. use have been illustrated in theaccompanying Although it is possible by this process to make l drawings,wherein: discs which are initially of the desired curvature, 4Fig-ure 1is a Side elet/anon of a disc made ac- 25 a great deal 4of trouble isexperienced by abrasive cording to one modicatlon of the presentlnvenmanufacturers by reason of the fact that vulcantion; ized ber isvery susceptible to changes. in at- 'Figure 2 is a side elevation of adisc embodying mOSpheric moisture eentent, Particularly When a secondmodification of the invention; and one side of the material has beencoated as is the Figure 3 illustrates the manner in which the 30 casewith the abrasive discs of this invention. It disc is employed. l hasbeen found, for example. that vulcanized liber .As will be seen byreference t0 Figure 3, the manufactured and sold by the Spaulding Fiberdiscs are mounted on a rotatable shaft I3 by Company of Tonawanda, NewYork, under the means of a nut Il which screws into the end oftrade-mark Armite, Which has been eXlJOSed t0 the shaft and pulls thedisc against a supporting the air at 70 F. at 50% relative humidityconpad Il which is commonly made of felt or soft talns 5.5% moisturewhereas the same fiber exrubber. The pad is attached to the spindle I3posed to air saturated with moisture contains through a supportingelement l2, which is ccm- 17.6% water. The ber is therefore a relativelymonly made of steel and is screwed tightly onto hysroscopic material andunfortunately when the the outside of the spindle I3. As illustrated in40 moisture content of a n-ber which has been coated the drawing, in usethe discs are applied to the onone side changes, the coated articlecurls. A workpiece I5 at a slight angle so that only a, porreduction inthe moisture content causes the ber tion of the periphery of the disc isin contact to curl with the coated side convex while -an inwith the workat any particular instant. It will l crease in moisture produces theopposite effect be apparent thatv the construction and method of andcauses the Vinitially Curved disc t0 become us'e of the disc are suchthat a disc backing must either fiat orl concave on the coated side. .Ashas bevery tough and relatively stiff though flexible. been Pointed Outabove. either an extreme amount In order to make the disc it snuglyagainst the of curvature with the abrasive side convex or a supportingpad II it is desirable that it should reduction in curvature below theminimum limit normally have a slight curvature with the abra- 50 0fabout V4 inch abreSiVe-eOnVeX makes the discs'- sive coated side convexso lthat when the nut -II unSatiSfeetOl'yis pulled into the spindle I3the disc will be caused It is accordingly an object of the present intohug the pad by reason of its springlike nature vention to provide amethod of stabilizing abracaused by the slight curvature. On the othersive discs having a backing 6011191181118 Vulcanhand, if the curvatureof the disc is .too great, the

ized fiber so that they are substantially unaffected by changes in theatmospheric conditions to which they are exposed. Another object of theinvention is to provide a method of treating abrasive discs to obtain acurvature in the desired `direction and of a predetermined amount. Stillanotherobject of the invention is to provide abrasive discs which have apredetermined amount of `curvature and which are substantiallyunaffected `by changes in atmospheric 'moisture' content with a sheetyof material which is impermeable to moisture vapor. I accomplish thisby any of several methods, one very satisfactory method being to dry thearticles to such an extent that they assume an excessive amount ofabrasive-convex curvature and then apply the water vapor-impermeablematerial by means of a water-soluble adhesive. One method winch I haveemployed very successfully is to cut the abrasive discs from the webmaterial, dry them until the, moisture content is-of the order of about-5.5%, as by heating in an oven for 21/2 hours at 125 F., and thenattaching a disc of paper-'coated metal foil with the paper side againstthe vulcanized ber. One such foil material which I have found to besatisfactory is made by the Reynolds Metal Company vand identified asMat Silver #30 Unifoil. This material consists of a sheet of paper about.002 inch thick adhesively attached to an aluminum foil which is about.001 inch thick.

In carrying out the process I rst coated the paper side of the Unifoilwith ordinary mucilage which I allowed to dry and I then moistened themucilage with water to make it tacky and pressed it against the back ofa disc 91/8" in diameter. I found that the small amount of water used tomoisten the mucilage, which brought the moisture content of the disc toabout 5.545%. was sufficient to make the disc assume a curvature suchthat the height of the cord formed by the y curled disc was inch.

Referring now to the drawings:

In Figure 1 there is shown a side elevation of a disc having a backing lconsisting of vulcanized fiber to one side of which a layer of abrasivegrains 2 is attached by a bond 3. The other side cf'the ber is providdwith a layer of water` vapor-impermeable foil 4 cemented to a paperlayer 5 which is attached to the vulcanized ber by an adhesive 6.

' In Figure 2 the backing consists of a layer of vulcanized fiber ihaving attached to one surface a layer of cloth 1 by an adhesive 8 andto the other surface a. water vapor-impermeable film 4 which is attacheddirectly to the fiber by adhesive 6. As in Figure 1, the abrasive grains2 are attached to the backing by a. bond 3, in this instance the grainsbeing directly applied to the cloth 1. The discs are provided with anarbor hole 9 for attaching to the spindle I3 in the manner illustratedin Figure 3. The amount of curvature of the discs shown in Figures 1 and2 is indicatedby` the height hl of the cord formed by the curved disc.

Although I have found the paper coated aluminum foil to be verysatisfactory. I may use other metal foils such as copper and tin and Ihave also made discs which are stable'to changes in atmospheric moisturecontent by substituting for the metal foil other waterlvapor-impermeable materials such as a sheet of plasticized vinylidenechloride which is made by the Dow Chemical 5 company and sold under thetrade name Saran,

or by using a specially prepared paperlike product .which is made by theRiegel Paper Corporation of New York city and sold under the designationM. P. Heat Seal Laminated Amber Di- 10 afane. Still another product oflthe Riegel Paper vCorporation which has been found t0 be satisfactoryfor use in our invention is one sold under the designation M. P. HeatSeal Pouch Stoc In applying these other materials I may eitherpreliminarily cement them to a. sheet of poper as was described withrespect to the aluminum foil, or I may attach them directly tothe discby a suitable cement as` shown in Figure 2 of the drawings. f

In the latter case the disc is brought to the desired curvature beforeattaching the water vapor-impermeable lm because it is necessary to useamadhesive made up with an organic solvent and such solvents do notmaterially affect the curvature of the ber. For example, the Saran" filmmay be attached by using a rubber cement which is substantially freefrom water.

It is to be understood that the paper-foil lm of Figure 1 may be usedwhere the backing is a cloth-fiber combination, as shown in Figure 2, orthat the film may be used without paper, as

shown in Figure 2, where the backing consists only of vulcanized liber.v

Where I use a metal foil such as aluminum foil I have found that thefoil is somewhat fragile- Iand at times may be pricked or scratched, forexample when it is put into contact with abrasive coated surfaces. Toprevent such rupturing of the metal foil I nd that it is sometimesdesirable 4 to apply a coat of lacquer over the metal foil.

One such lacquer which I have found to be satisfactory has the followingcomposition, the proportions being parts by weight:

Parts 1/2 sec. nitrocellulose 16 Estergum- 6 'Iricresyl phosphate 3Butyl alcohol 11 Ethyl allnhnl 7 Butyl acetate 25 Toluol 32 In applyingsuchlacquer I first dilute the composition described above with an equalpart of 56 ethyl acetate and then spray this thinned lacquer overthevmetal foil. I have found that one coat ,is suiiicient for my purposeand that a satisfactory weight is in the range of 3/4 to 11/2 grams ofthe lacquer solids per 100 square inches of foil.

e0 'Ihis corresponds to about 6 to 12 grams of the thinned lacquer per100 square inches of surface since the' thinned lacquer contains U15/2%soivents.

It will be apparent that I may apply the lacquer either before or afterthe foil has been stuck to the disc. It will also be apparent thatalthough I` have described the application of the lacquer as a spray, itmay be put 'on otherwise as by roll coating, in which case a lacquer maybe employed of the `composition given in the formula above and thethinning described for spraying is unnecessary.

As I have indicated, the .backing may be either wholly vulcanized fiberor it may be a combination which includes vulcanized ber such as aadhesives.

- combination of vulcaniz also use other backing materials which includevulcanized fiber, such as a combination of cloth,

paper and vulcanized liber, as is described and claimed in my Patent No.2,320,139 or I may even use conventional backings such as paper or clothwhere the coated articles are to be employed for other purposes as inthe manufacture of abrasive belts, sheets, cones or the like. Where berI backing by any suitable adhesive such as glue or a synthetic resin orby a combination of different For example, they may be directly attachedto the backing by a so-called making coat of glue and then a second orsizing coat of a synthetic resin such as a phenol-aldehyde condensation`product may be applied over the abrasive grains and the glue makingcoat. Where a combination backing is used, the cloth backing may becemented to the iiber by any suitable adhesive such as glue, aphenol-aldehyde resin, or a urea-aldehyde resin.

Although I have .described my invention by reference to certain specicmaterials and methods, it is to be understood that, the invention is notto be limited to the specic details described and shown in the drawingsbut rather is to be-considered of the scope defined in the followingclaims.

I claim 1. In a method of making an abrasive disc the steps whichcomprise bonding a layer of abrasive grains to a backing comprisingvulcanized fiber, forming a disc from the abrasive coated backing,drying the article to such an extent that the ed ber and cloth. I may'abrasive coated side of the article is convex and the article has aradius of curvature which is smaller than that desired in the finishedarticle, and attaching a sheet of paper adhesively joined to a lm whichis substantially impervious to water vapor on the vulcanized ber on theside of the backing which is opposite the abrasive coat-l ing by anadhesive containing water whereby the water in the said adhesivepenetrates the vulcani'zed ber and causes the article to assume apredetermined curvature of greater radius than that of the driedarticle.

2. In a method of makin-g an abrasive disc the steps which comprisebonding a layer of abrasive materials to a web of backing materialcomprising vulcanized fiber, cutting a disc from the abrasive coatedweb, drying the disc to such an extent that the abrasive coated side ofthe disc is convex, and adhesively attaching a preformed iilm which issubstantially impervious to water vapor to the vulcanized fiber on theside of the backing which is opposite the abrasive coating.

3. In a method of making an abrasive disc the steps which comprisebonding a layer 'of abrasive materials to a web of backing materialcomprising vulcanized ber, cutting a disc from the abrasive coated web,drying the disc to such an extent .that the abrasive coated side of thedisc is convex and the disc has a radius of curvature which is smallerthan that desired in the nished article, and attaching a film which issubstantially impervious to water vapor to the vulcanized ber on theside of the backing which is opposite the abrasive coatingy by anadhesive containing water whereby. to increase the radius o1 steps whichcomprise bonding a layer of abrasive materials to a web of backinglmaterial com- Drising vulcanized ber, cutting a disc from the abrasivecoated web, drying the disc to such an extent that the abrasive coatedside of the disc is convex and the disc has a radius of curvature whichis smaller than that desired in the iinished article, and attaching asheet of paper adhesively Joined to a sheet of metal foil to thevulcanized fiber on the side of thel backing which is opposite theabrasive coating by a water-soluble adhesive, the amount of water in theadhesive being such as to cause the finished disc to assume a curvaturesuch that the height of a cord formed by a disc about 9 inches in therange of about A to 1 inch.

5. In a method of making an abrasive disc the steps which comprisebonding a layer of abrasive materials to a web of backing materialcomprising vulcanized ber, cutting a disc from the abrasive coated web,drying the disc to such an extent that the abrasive coated side of thedisc is convex and the disc has a radius of curvature which is smallerthan that desired in the nished article, and attaching a. sheet of paperadhesively joined to a sheet of aluminum foil to the vulcanized iiber'on the side of the backing which is opposite the abrasive coating by awater-soluble adhesive, the amount of water in the adhesive being suchas to cause the finished disc to assume a curvature such that the heightof a cord formed by a disc about 9 inches in diameter is within therange of about 1A to 1 inch. f

6. An abrasive disc comprising a backing comprising vulcanized ber, alayer of abrasive grains bonded to one side of the backing, anda lmwhich is substantially impervious to water vapor adhesively attached tothe vulcanized ber on the side of the backing which is opposite theabrasive coating, the moisture content of the vulcanized fiber beingsuch that the disc has a curvature in such direction that the abrasivesurface is convex and of such an amount that the height of a chordformed by a disc about 9 inches in diameter is within the range of aboutV4 to 1 inch, the vulcanized ber being so sealed in by kthe bond for theabrasive grain on the one side stantially impervious to water vaporattached to the vulcanized ber on the side of the backing which isopposite the abrasive coating by a water-soluble adhesive, the moisturecontent of the vulcanized iiber being such that the disc has a curvaturein such direction that the abrasive surface is convex and of such anamount that the height of a chord formed by a disc about 9 inches indiameter is within the range o! about 1/4 to 1 inch, the vulcanized berbeing so sealed in by the bond for the abrasive grain on the one sideand the nlm on the back that the curvature o! the disc remains withinthe designated range even when the disc is exposed to wide variations inatmospheric moisture conditions.

8. An abrasive disc comprising a backing comdiameter is within prisingvulcanized ber, a layer of abrasive grains bonded to one'side ofthebacking. and a layer of paper adhesively joined to a sheet of metaltoil v the disc has a curvature in such direction thatl the abrasivesurface is convex and of such an amount that the height of a chordformed by a disc about 9 inches-in diameter is within the range of aboutWto 1 inch, the/vulcanized ber being so sealed in by the bond for theabrasive grain on the one side and the lm on the back that the curvatureof the. disc remains withinv the designated range even when the' disc isexposed to wide variations in atmospheric lmoisturen:

conditions.

9. An abrasive disc comprising abackirrg comprising vulcanized ber, alayer of abrasive grains bonded to one side of the backing, and a layerof paper Vadhesive joined foil attached to the vulcanized ber on theside of the backing which is oppositevl the abrasive coating by awater-soluble adhesive, the moisture content o1 the vulcanized ber beingsuch that i the disc has a curvature in such direction that the abrasivesurface is convex and of such an amount that the height of a chordformed by a disc about 9 inches in diameter is within the range of about1/4 tol inch, the vulcanized ber being so sealed in by the bond for theabrasive grain on the one side and the lm on theI back that thecurvature of the disc remains rwithin thel designated range even whenthe disc is ex-Y posed to wide variations in atmospheric moisture lconditions.

10. An abrasive disc comprising a backing comprising vulcanized ber andcloth. a layer of abrasive grains bonded to the cloth, and a lm which issubstantially' impervious to water vapor .adhesively attached to theother side of the vulcanized ber, the moisture content of the vulcanizedber being such that the disc has 'a curvature in such direction that theabrasive surface is convex and of such an amount that the height of achord formed by a disc about 9 inches in diameter is within the range ofabout 1A. to 1 inch. the vulcanized ber being so sealed in by the bondfor the abrasive grain on the one side and the lm on the back that thecurvature of the disc remains within the designated range even when thedisc is exposed to.wide variations in i atmospheric moisture conditions.

to a sheet oi aluminum tlf 2,431,258

11. An abrasive disc comprising a backing consisting of vulcanized ber,a layer of abrasive grains bonded to one side of the ber, and a lm whichis substantially impervious to water vapor adhesively attached to theother side of the vulcanized ber, the moisture content of the vulcanizedber being. such that the disc has a curvature in such direction that theabrasive surface is'convex and of such an amount that the i/ height of achord formed by a disc about 9 inches ,f ,in diameter is within. therange of about V4 to 1 f?, inch, the vulcanized ber being so sealed inbyA the bond for -the abrasive grain on the one side and the lm ong' theback thatthe curvature of the disc remains within the designated rangeeven when the `disc is exposed to wide variations atmosphericmoisture-conditions. 12. An abrasive disc comprising a. backing comprising vulcanized ber, a layer of abrasive grainsl bonded to one sideof the backing, a layer o1 pal per adhesively joined to a sheet ofaluminum foil attached to the vulcanized ber on the side of the backingwhich is opposite the abrasive coatlacquer on'the exposed side of thealuminum foil, the moisture content of the vulcanized ber being suchthat the disc has a curvature in such direction that the abrasivesurface is convex and of such an amount that the height of a chordformed by a disc about 9 inches in diameter is within the range of aboutto llincl'r'thel f vulcanized ber being so sealed in by the bond ,forthe abrasive grain on the one side and the lm on the back that thecurvature of the disc remains within the vdesignated range even when thedisc is exposed to wide' variations in atmospheric moisture conditions.

HENRY fP. KIRCHNER.

4 REFERENCES CITED The following referencesare of record in the l NumberName Date 2,269,661 Gurwick Jan. 13, 1942 2,190,479 Moore Feb. 13, 19401,759,168 Okie May 20, 1930 2,152,392 Tone Mar. 28, 1939 1,966,473Wooddell a July` 17, 1934 2,085,211 y BuddSet al June 29, 1937 ing by awater-soluble adhesive, and a coat of

